Im sure this questions has been asked loads of times already but after my many hours of searching and reading reviews I still cant decide which one of these two CPUs i would be better off at getting..? So i thought i would ask you wonderful people, So the main use of the CPU will be heavy video editing/rendering in CS5 premiere with fairly big files and other associated programs in CS5. So which would be better the i7-3820 or i7-2700k...?
Get the 2600k, and spend the rest on an nvidia GPU with CUDA.
I'm interested in this comment as I'm an avid CS5 user and my experience with CUDA has been less than positive. For the mercury playback engine (GPU enhanced) in Premiere Pro it certainly does accelerate editing but is limited by the very restricted set of effects where GPU acceleration is possible. With a 2700k, I find it's almost always fast enough for real-time preview/editing in PPro, so disabling CUDA doesn't have much practical effect (if any).
For rendering, my experience with CUDA acceleration is that it is both unstable and gives rise to significant artefacts. Effects rendered incorrectly, weird stuff happening in the final output, timings wrong, etc, all fixed when you switch to CPU rendering. On the basis of my experience, I advise to steer clear of CUDA with CS5 - it seems immature and at the moment, more trouble than it's worth. A further point in the CPU vs GPU rendering debate in CS5 is After Effects. Hardly anything in AE is CUDA accelerated, which is a strong argument for a powerful CPU. Particularly as rendering times in AE can be incredibly long.
As for the OP's question, if it were my money, I would favour the 3820. Not because of any intrinsic benefit over the 2600k/2700k, but because the motherboard gives you an upgrade path to hex-core if and when you have budget. CS5 really is one of the situations where the additional power of a hex core CPU can really tell. (With this in mind, I would plump for a 3830k but assume that since you're considering a 3820, budget doesn't allow for a 3830k).
If you have no intention of upgrading to a hex core, the 3820 has no real advantages over a 2700k. In this case I'd get the latter since it can be easily overclocked. From personal experience, I confirm that 2700k is a good match for CS5.
Just to give you another option.... Can you afford to wait until Ivy Bridge comes out? If so, the prices are said to be about the same as the Sandy Bridge equivalents and there's a definite performance advantage.